The use of double metal cyanide catalysts in the preparation of high molecular weight polyols is well-established in the art. For example, U.S. Pat. No. 3,829,505, assigned to General Tire & Rubber Company, discloses the preparation of high molecular weight diols, triols etc., using these catalysts. The polyols prepared using these catalysts can be fabricated to have a higher molecular weight and a lower amount of end group unsaturation than can be prepared using commonly-used KOH catalysts. The '505 patent discloses that these high molecular weight polyol products are useful in the preparation of nonionic surface active agents, lubricants and coolants, textile sizes, packaging films, as well as in the preparation of solid or flexible polyurethanes by reaction with polyisocyanates.
Certain thermoset polyurethane elastomers produced using triols made by DMC catalysis are also known. More specifically, U.S. Pat. No. 4,242,490 discloses the preparation of such elastomers by reacting a DMC catalyst-prepared polypropylene ether triol having a molecular weight of from 7,000 to 14,000, ethylene glycol, and toluene diisocyanate in a specified range of molar ratios using either a prepolymer process or a "one-shot" process.
Methodology for preparing TPU elastomers is well-established in the art. By way of illustration, U.S. Pat. No. 4,202,957 discloses polyurethane polyether-based elastomers, made using a select group of polypropylene oxide-Polyethylene oxide block copolymers, which this patent states are thermoplastic, recyclable and possess high temperature degradation resistance thus permitting fabrication by injection molding. Unfortunately, the TPU elastomers prepared in accordance with prior art methods, such as that disclosed in U.S. Pat. No. 4,202,957, are generally not as soft as might be desired.
Heretofore, the use of high molecular weight polyols made with double metal cyanide catalysts in combination with chain extenders in the preparation of thermoplastic elastomers, particularly thermoplastic elastomers characterized by enhanced softness, has not been known based upon the knowledge of the present inventor The discovery of such soft elastomers would be highly desired by the elastomer manufacturing community.